Visible-Light-Driven Synthesis of Dihydroaurones from Aromatic Diazo Compounds.

Dihydroaurones, which are derivatives of aurones, exhibit similar biological activity. Although there are many synthetic methods for dihydroaurones, ecofriendly methodologies that circumvent the use of precious metals still need to be explored. In this work, a catalyst-free, visible-light-driven synthesis of dihydroaurones has been developed through the cyclization of aromatic diazo compounds. The reaction proceeded smoothly under mild conditions, resulting in a series of dihydroaurones in moderate to high yields. Mechanistic investigation suggests that this process involves a radical-pair Stevens rearrangement.